A portable computer (such as a notebook computer) generally is powered via an external power transformer or a battery, and the external power transformer or battery generates heat due to efficiency loss or increasing load current. When the heat generation increases, the heat dissipation effect has to be enhanced generally by enlarging the heat-dissipating apparatus or surface; or increasing cooling airflow. However, if the ambient temperature is high, the heat generated from the external power transformer or battery cannot be dissipated easily, and thus the performance and operation life of the portable computer will be affected while the portable computer is continuously operated in a high-temperature environment.
For meeting the requirements of power consumption and high ambient temperature when the portable computer is operated at the maximum capability, the power output of the external power transformer or battery is usually used to meeting the power consumption for the portable computer operated at the maximum capability in the highest ambient temperature, so that not only the production cost is increased, but also the size of the external power transformer or battery and the space required for its heat dissipation have to be increased, thus failing to satisfy the requirements of lightness, thinness and smallness for the portable computer.
Further, due to different power consumption for different models of portable computers, even if the portable computers all have the same connectors, one single type of the external power transformer or battery is not generically applicable to the portable computers of different models.